Reinforced carton



June 2, 1964 BRUNDAGE 3,135,452

REINFORCED CARTON Filed April 23, 1962 2 Sheets-Sheet l I N VEN TOR. 'fi/c/m/ap /7 5/60/104 @4- Afro f/VEYS United States Patent 3,135,452 REINFORCED CARTDN Richard M. hrundage, Buena Park, Qalifi, assignor to Menasha (Zorporation, a corporation of Wisconsin Filed Apr. 23, 1962-, Ser. No. 139,536 '7 Claims. (Cl. 229-14-) This invention relates to reinforced cartons, and included in the objects of this invention are:

First, to provide a reinforced carton which utilizes cardboard of. the type comprising two surface sheets of paper and a corrugated paper interposed therebetween, wherein a reinforcing member is interposed between the corrugated paper and one of the surface sheets in those areas of the carton blank destined to form the side walls of the finished carton, thereby to form a carton with increased crushing strength in a direction perpendicular to its bottom and top sides as well as to form a carton with increased strength in end-to-end and side-to-side directions.

Second, to provide a reinforced carton which is particularly adapted to utilize as the reinforcing member a cardboard or paper stock impregnated with sulphur or other stiffening material.

Third, to provide a reinforced carton which is not altered in appearance by reason of the reinforcing member as the reinforcing member is concealed, thereby permitting the use of an inexpensive reinforcing member which may not, in itself, be attractive in appearance, or which might, if exposed, impair printing operations.

Fourth, to provide a reinforced carton wherein the reinforcing member may be water-repellent or have high wet strength so as to impart high wet strength to the carton, and permit its use for produce or other products which must be carried and stored in a wet state or damp environment.

Fifth, to provide a reinforced carton which is inexpensive of manufacture in that the reinforcing member may be introduced as the corrugated carboard is being formed and form in the carton blank a continuous strip of a width to embrace the side and end-forming panels of the carton blank.

With the above and other objects in view, as may appear hereinafter, reference is directed to the accompanying drawings in which: 7

FIGURE 1 is a perspective view of a reinforced carton construction in accordance with the present invention, and with a portion of the side and top walls broken away to illustrate the internal construction;

FIGURE 2 is an enlarged,fragmentary, perspective view with the upper edge in section, taken in the plane 2-2 of FIGURE 1;

FIGURE 3 is a plan view of the carton blank;

FIGURE 4 is an enlarged fragmentary, sectional view taken through 4-4 of FIGURE 3;

FIGURE 5 is an enlarged fragmentary, taken through 5-5 of FIGURE 3.

The reinforced carton may, except for the reinforcement incorporated therein, be a conventional carton. For example, the carton may comprise side wall panels 1 and end wall panels 2 joined consecutively or in series, and provided at their lateral sides with bottom and top side flaps 3 and bottom and top end flaps 4, respectively. One end of the series of panels is provided with a connecting tab 5 so as to be joined to the opposite end of the series in order that the side and end panels 1 and 2 may form a square or rectangular enclosure.

The panels l and 2 and flaps 3 and 4 comprising the carton are formed of corrugated cardboard comprising an inside sheet 6 and an outside sheet 7 and a corrugated core 3. The corrugations of the core 8 preferably extend transversely with respect to the side and end wall panels.

sectional view 3,135,452 Patented June 2, 1964 "ice In the exercise of the present invention a reinforcing strip 9 is introduced between the outside sheet 7 and the corrugated core 8. The reinforcing strip 9 is at least equal to the width of the side and end panels 1 and 2, and preferably includes marginal portions 1t which overlap slightly into the bottom and top side and end flaps 3 and 4. The reinforcing strip 9 is preferably formed of pulpboard which is somewhat thicker than the sheets 6 and 7. The pulpboard is impregnated with a reinforcing material, for example, sulphur. Sulphur greatly increases the strength of the pulpboard and is moisture-resistant so that the wet as well as the dry strength of the pulpboard is greatly increased. Sulphur is also relatively inexpensive. Alternatively, the pulp board may be impregnated with various plastics, the only disadvantage being that most plastics are more expensive than sulphur.

Inasmuch as the finished cardboard is uniform in thickness, the corrugations underlying the reinforcing strip 9 are deformed, as indicated by ll.

In order that the carton blank may be folded into a carton, the side wall and end wall panels 1 and 2- are provided at their iunctures with double creases 12, and a reinforcing strip 9 is pressed inwardly so that at t e corners of the carton the reinforcing strip 9 forms a W, as shown best in FIGURE 2. The connection between the marginal portions 10 and the intervening portion of the reinforcing strip 9 are similarly formed, as shown in FIGURE 4.

The reinforcing strip 9 may be made the exact width of the panels 1 and 2 so that the flaps may be joined to the panels by conventional single creases. However, the marginal portions 19 further increase the strength of the finished carton against vertical crushing loads, particularly when a number of cartons may be poorly stacked. The side margins 19 also facilitate the manufacture of the carton blank, as the presence of these marginal portions eliminates the need of accuracy in centering the reinforcing strip 9 with respect to the junctures between the side panels and the flaps.

It should be pointed out that the reinforcing strip 9 is entirely concealed so that its location is not obvious in the cardboard prior to die cutting the carton blank. The presence of the reinforcing strip 9 does become evident when printing the carton blank for the reason that the presence of the strip 9 provides an improved surface on which to print.

While a particular embodiment of this invention has been shown and described, it is not intended to limit the same to the exact details of the construction set forth, and it embraces such changes, modifications, and equivalents of the parts and their formation and arrangement as come within the purview of the appended claims.

What is claimed is:

l. A reinforced carton, comprising:

(at) end and side wall panels foldably series;

(b) bottom and top flaps hinged to said panels and forming therewith fold lines;

(0) said panels and flaps formed of laminated paper including an outer sheet, an inner sheet, and corrugated paper therebetween;

(d) and a reinforcing member interposed between one of said sheets and said corrugated paper and adhered thereto, said reinforcing member extending continuously through said end and side panels, foldable therewith, and occupying the full width of said panels between said bottom and top flaps with its edges adjacent said fold lines;

(e) said reinforcing member being a sheet of solid stiff material of substantially less thickness than the depth of said corrugations;

connected in (f) that portion of said corruguated paper coextensive with said reinforcing member being partially crushed to reduce the height of the corrugations by an amount substantially equal to the thickness of said reinforcing member, whereby the thickness of said panels and flaps are equal and the entire carton is of uniform thickness throughout.

2. A carton as defined in claim 1, wherein:

(a) said reinforcing member comprises a solid sheet of felted fibrous material impregnated with a stiffening agent.

3. A reinforced carton as set forth in claim 1, wherein:

(a) said fold lines are adjacent and beyond the edges of said reinforcing member whereby said reinforcing member does not extend into said bottom and top flaps.

4. A reinforced carton as set forth in claim 1, wherein:

(a) said fold lines are located adjacent and within the side edges of said reinforcing member whereby the side margins of said reinforcing member extend into said bottom and top flaps.

5. A reinforced carton blank, comprising:

(a) laminated paper including an outer sheet, an inner sheet, and corrugated paper therebetween;

(b) a longitudinally extending reinforcing member comprising a panel of solid felted fibrous material impregnated with a stiffening agent and interposed between and adhered to one of said sheets and said corrugated paper;

(c) that portion of said corrugated paper coextensive with said reinforcing member being partially crushed to reduce the height of the corrugations thereof by an amount substantially equal to the thickness of said 4 reinforcing member whereby the entire blank is of substantially uniform thickness throughout;

(d) said blank having longitudinal score lines adjacent the side margins of said reinforcing member and spaced transverse score lines to form areas completely occupied by said reinforcing member, and destined to become the sides and ends of a carton;

(e) said blank extending laterally beyond said longitudinal score lines to form side strips destined to be cut to form top and bottom flaps of a carton.

-6. A reinforced carton blank as set forth in claim 5,

wherein:

(a) said score lines are adjacent to and beyond the edges of said reinforcing member, whereby the portions of said blank destined to become bottom and top flaps are free of said reinforcing member.

7. A reinforced carton blank as set forth in claim 5,

wherein (a) said score lines are adjacent and within the side edges of said reinforcing member whereby the side margins of said reinforcing member extend into the portions of said blank destined to become the bottom and top flaps of said carton.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A REINFORCED CARTON, COMPRISING: (A) END AND SIDE WALL PANELS FOLDABLY CONNECTED IN SERIES; (B) BOTTOM AND TOP FLAPS HINGED TO SAID PANELS AND FORMING THEREWITH FOLD LINES; (C) SAID PANELS AND FLAPS FORMED OF LAMINATED PAPER INCLUDING AN OUTER SHEET, AN INNER SHEET, AND CORRUGATED PAPER THEREBETWEEN; (D) AND A REINFORCING MEMBER INTERPOSED BETWEEN ONE OF SAID SHEETS AND SAID CORRUGATED PAPER AND ADHERED THERETO, SAID REINFORCING MEMBER EXTENDING CONTINUOUSLY THROUGH SAID END AND SIDE PANELS, FOLDABLE THEREWITH, AND OCCUPYING THE FULL WIDTH OF SAID PANELS BETWEEN SAID BOTTOM AND TOP FLAPS WITH ITS EDGES ADJACENT SAID FOLD LINES; (E) SAID REINFORCING MEMBER BEING A SHEET OF SOLID STIFF MATERIAL OF SUBSTANTIALLY LESS THICKNESS THAN THE DEPTH OF SAID CORRUGATIONS; (F) THAT PORTION OF SAID CORRUGUATED PAPER COEXTENSIVE WITH SAID REINFORCING MEMBER BEING PARTIALLY CRUSHED TO REDUCE THE HEIGHT OF THE CORRUGATIONS BY AN AMOUNT SUBSTANTIALLY EQUAL TO THE THICKNESS OF SAID REINFORCING MEMBER, WHEREBY THE THICKNESS OF SAID PANELS AND FLAPS ARE EQUAL AND THE ENTIRE CARTON IS OF UNIFORM THICKNESS THROUGHOUT. 